Telephony.



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D. s. HULFISH.

TELEPHONY.

`APPLICATxcm FILED SEPT.30.1912.

Patented Mar. 27, 1917.

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`TELEPHonr.

APPLICATION HLED SEPT. 30, ISI-2- Patented Mar. 27,1917

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Patented Mar. 27, 1917.

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D. S. HULFISH.

I atented Mar. 27, 19172 I3 SHEETS-SHEET 6.

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1,220,228.V I Patent@ Mar. 2f, 1917.,

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D. S. HULFISH.

TELEPHONY. APPLICATION FILED SEPT-V30. 1912.

Patented Mar. 2.7, 1917.

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`|ELEPH0NY.

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Pa bented Mar. 27, 1917;

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TELEPHONY. y APPLICATION` FILED SEPT 30| |912.

Patented Mar. 27, 1917.

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TELEPHONY. APPLICATION FILE SEPT. 30. i912.

PatentdMar. 27, 1917.

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D. S. H'ULFISH.

TELEEHUNYn APPucATmN FILED SEPT. 30. |912.

Patented Mar. 27, 1917.

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'circuits will UNITED sTATEs PATENT OFFICE.-

DAzvrp s`. HULFISH, OF TORONTO, ONTARIO, CANADA, AssIGN on To CANADIANINDE PENDENT TELEPHONE COMPANY, LIMITED, OF TORONTO, C ANADA, ACORPORATION OI'l IOANADA.

TELEPHONY.

Specification of Letters Patent.

Pa l'entod Mar. 27, 1917.

Original application med my 1a, une, serial No. 696,902. Renewed Augtst7, 1915, serial No. 44,292. Divided and this application filed September30, 1912. Scrirl No 723,229.

To @Il 'whom it may concern:

Be it known that I, Davm S. Hl'nrisu, cnineer, a citizen of the UnitedStates of merica, residing at Toronto, in the county of York and Provineof Ontario, Canada,

,have invented certain new and useful Improvements` in Telephony, Ofwhich the following is a specification and a description of the mannerand process` of constructing,r and using the same, intended to be insuch filll, clear, concise, and exact terms as to enable an personskilled in the art to malte and us'e t e same.

My invention relates to telephone systems in general andto the a)plication ot' methodsl and a iparatus for telephone switching incentral Ofiices of telephone exchanges, and 'this application is adivision of my prior application Serial No. 696902, vfiled May 13, 1912,and renewed as Serial'No. 44292, Aug. 7,` 1915. In some of its details,itis particularly adapted to systems of the Lorii lmer type of automatictelephone devices and I have shown it in this aplplication applicdspecifically to a system o circuits for the Larimer 7 type of'autoniaticapparatus with suggestions from time to time as 4to the generalapplication of certain features of `my invention to the general artof-telephony in central'olices whetherautomatic or manual,

My invention has for itsl Objects the fo1-.

lowing: f-

(B) A. method of calling among lines entering an. automatic telephoneexchange whereby the orderof answering,r Icontemporaucously existingcalls'mayI be varied from time to time.

(C) A combined sequence switch and division starter. i i

' (D) A system of tcst circuits'for deter miningl tho busy or idleconditionof a tested circuit` whereby the tested circuit may have eitherof two potentials impressed uponit during; its busy condition andthetesting reject it if it bears either potcntal. i

(F) An improved system for testin a 'tclepl'ouc `line for busy or idlecondition, md the subsequent adji'istrnent of automatic switches inaccordante with the result of the test, including a locking relay forrecording the,rcsultofLthe transient test, the

relay being held l( cked for a sufficient time for reliable operltion ofthe automatic switches requiring control subsequent to the test anddependently upon the test.

(G) An impl-Ovid system of comlnutators and associated circuits forringing code ringingr upon party lires in an automatic telephoneexchange.

(H) An' improv 3d system of controlling circuits for an aut )matictelephone Connec tive apparatus, controlled by Vthe two telephones ofthe connection, and controlling the release of the connection at theWill either of the tclopl one users.

(K) A system of lamp signals for a'n aLitomatic telephone axe-harige inwhich a different order of signals is produced when the line called foris bu sy as compared with the signals produced vhen the line called foris tested and `founo idle; also, an improved signal in a set of4 lampswhereby two lamps each having a defirite meaning when burn.- ing alonemay be caused to burn simultaneously to express a third and independentilnprovld timer device or slow 'connection with an automatic lamp alarmand release device whereby the attendant in charge of an autoinaticexchange may disable either the autcmaticrelease functions of' the.telephone oi ice or the .lamp alarm fllnctionsof the telephone office,but not both. p

' (Q) `An improved multiple brushjor an automatic switch) enga-ging apluralityof Contact points on they same level and Closing through -thema 4plurality of simultaneous circui l (R) A brush arrfngement bywhlchtwo independent multiple' brushes act uponthe i .106

same level of-contact points and close simulitaneous and independentcircuits through `each circuit being cle'of' the switch,

the same level of oints, closed twice in a single cy one closure foreach multiple brush. a

(SA) A system 'of mutual circl its between two automatic switches, suchat the return of either to normal. will 'return the other to normalalso.

(SB) A system of main circuits and of auxiliary circuits in an automaticexchange, such that the control of an automatic switch normally by aline and its telephone is substituted by a central ofiice auxiliarcircuit in case the switchl has no connected line.

(SC) A. system of circuits by which the pilot switch when at normalrestores otherswitches to normal, namely, the primary connector and-,thesignal controller.

(SD) A system of driving devices and circuits `for a. timing devicewhereby one timer may bedriven at diiferent speeds at different times. l

(SE) I provide a division starter with a timing device whereby a seconddivision will be started in case the first does not respond promptly.

(SF) A novel .disabling circuit ior a di` I vision starter when alldivisions are busy.

(5G) A method ofusingduplicated devicesor electrical circuits having acommon estination by using them in order of--rota- (SH) A method ofusing a group of electrica-l circuits having a common destination bydividing them into t-wo small groups', one small group used in rotationand the 'remaining small group used' ashan overflow group and used innumerical order of precedence.

(SM) A system and method of metering calls in. which a. 'call isrecorded' upon the meter of the calling line only as a result of theresponse of the called line;

(SN) A detail of metering 'system for eneral application in telephoneexchanges y which certain lines may be designated as free servicel linesandy calls terminating upon these lines lwillnot register upon the'.meterof the calling line when the free l service vline responds.

A *System forseizing al -busvy line with disregard o f the guard-ingcondition.

ibers station su itable for a party line havprimary 2 shows-the circuitsof the pilot andthousands or ringing register.

switc l' "Figa 3 showsthe circuits-of the relays,

commutatore, division I other apparatus.

timer and sundry SQ) improved rtlelephone'j for a'sub- I ephone Fig. 7shows the circuits of the line relays constltutin ,the decimalindicator.

Fig. 8 sgiws 'the circuits of the decimal controller.'

Fig. 9 shows the circuits of the division starter which is also thepermutation con-VA troller for the line relays or decimal indicator.

Fig. 10 shows the circuits of a telephone for aline having but onetelephone.

Fig. 11 shows a simplified diagram of the circuits for-conversation andfor release under subscribers control.

Fig. 12 shows the circuits of the rotational busy test.

Figs. 13, 14 und 15 show details of free meter lines.

Fig. 16 shows the circuits of :l telephone for a party line.

Fig. 17 show-s a party line telephone having interference features forparty-line. I

In the figures, numerals smaller than l100 i are not strictly vreferencelabels within the ordinary meaning of the term; they. are nu#l lneralsindicating-theA order or relation of the parts adjacent to-which theyare found; or to which they directly pertain', as indicating the orderof Contact points in a row, or the order Aof rows in'u contact bank; forexample, the numerals 1-tof44 in Fig. are 'stampedupon the apparatus asbuiltand used, and'form a part of the apparatus illustrated by thedrawing. Reference numerals 101 to 199 have been reserved for conductorsentering the pilot switch, 200 to 399 for apparatus parts, and 400 andhigher for miscellaneous conductors. Like numerals refer Fig. 4 showsthe circuits of the signal controller.

Fig. 5 shows the circuits of the. interconnector or trunk selector.

Fig. 6 shows the circuits of the secondary connector or B-switcl1.

.so l

The switches.

` The switches are of three types, called the cylinder type,`theregister type and the coiniuutatortype.'

A switch of 'the'cylinder type is illustrated in Fig.: The horizontalrows of small `circles represent' the fixed contact' points projectingVfrom Athe.', clevelopcdinner surface of an 4annular casting ofinsulating material; upon these. contact points there move horizontallyfrom leftv to righta set of brushes,I shown in the figure as small flatparallelo( grams restn upon the points ofthe first vertical set opoints. A controlling magnet or clutch magnet213 has an armature adaptedtoengage a notched disk to restrain the passing through it, its armatureis withdrawn from the notched disk and the disk is permitted or causedto revolve., wrrying with it the brushes of the associated cylinf der.rlhe disk (and therefore the brushes of the switch) may'stop only inpositions corresponding to notches in the peril'ihery of the disk, andthese notches tl-ierefore.'represent the only possible. stop positionsof the brushes of the switch.

`In the primar)Y connector of Fig. l the stop positions of the brushesare all but one in the first quadrant of revolution, as indi'- cated bythe location of eleven notches in the clutch disk.

In the pilot switch of Fig. 2 there are fourteen stop positions,irregularly distributed. The vertical sets of contacts of the cylinderAare ynuinliered horizontally Lto-44, the stop positions of theln'ushes'are numbered in the. line above, Lto-14, cach number appearingtwice, over each 'of the two adjacent sets of points occupied b v themain set of pilot brushes in each of the indicated stop positions; thebrushes uornially when not in use upon No. 1 stop position, or contactsets l and 2. cylinder points are numbered l-to-l-*l from top to bottom.at the left.

The pilot switch, of Fig. 2 has also a set of auxiliary brushes, threepairs on 3rd, 7th, and 9th levels, respectivebf resting nornialhyy onpoints of 34th and 255th sets and moving with the main brushes. ofthe7th level are connected b v a wire to the auxiliarybrushes of, the samelevel.

In the signal transniitter controller of Fig. ,4` the clutch disk hasfour' notches. The

`disk is geared to the brushes in the ratio of one revolution of thedisk for two lrevolu tions of the brushes. The complete cycle ofoperations of theswitch is effected in two complete revolutions of:thelqrushes, or one revolution of the disk.l The stop positioner ofthebrushes are: normal position on con tart set No. l first stop positionon contact set No. 43 ust before the end oil the first rev#olution;,second stop position ou contact.. set No. 1; third stop'position on .Contact set No. 43 just before the .end o-f'the secondrevolution.

r[he intereonnector ond-ary connector ot Fig, G are switches sunl- 'larto that ot Fig. 1. The division starter.

of Fig. l) is a switch similar to that of Fig. 2 but with a differentdistribution. o'f stop notches, without a register, and with a single.

The horizontal rows ofi 'lhe main brushes `of Eig. 5 and the sccpoint,middle of bottom row of bank, connected to conductor 105. When twopoints nre engaged by tno connected brushes, the points are indicated bya hyphen connection, thus: pilot points 1X13-12 where the 4engagedpoints are i1 the sume 'vertical row; or pilot points QYXB-QSXB, pilotpoints 39X7-7X7, where t 1e engaged points are not in the same verticilrow.

A switch of the register type is illustrated inFig. 1. at the top. .Thearcs of small cirY cles represent rows of fixed Contact points, uponwhich move the brushes shown as small rectangles up )n set'No. 0 of thepoints. The brushes are car ried by the ratchet, which is under springte ision against the pallet, and' which is permitted to movestep-by-step under control of the register magnet 214. This register comlvlete, is carried by the mechanism carry-iur the cylinder brushes towhich the register parts are wired. It is restored to normal positionafter having been operated", by mechanical devices which restore itduring 'he second quadrant of re\olution of lhe c utch disk.

The ringing register of Fig. 2, is in fixed positioinebut is loert-edadjacent to an associated cylinder sw tch, and is restored to normal bvthe retu `n of the adjacent rvlinder switch, such as he pilot switch ofFig. 2. 'Tl brushes of the register' are reversed, ii ing om right toleft.

i luf i gisters of "igs. 5 and (l are sin'iilar to that of Fig. ard are.similarly restored.

A switch of the ioinniutator type is illustrated in Fig. S, the decimalregister controller. The develtped ronunutator ringof long segnunt 2552ar d fifty smaller segments` with its associated l rushes, coiuluetors,relay and clutch, form tire decimal register controller as' a whole,whose function it is to operate the. decimal register ol' va starteddivision to .seizure of the. callirg line.

There; is one deiimal register controller foreach switchboard.sectiou orgroup of divisions, one such controller thus serving all'l of al' groupof lines and` controlling. the decimal registcrsiot all 4thecorresponding group ofconnectivo divisions. y

The decimal register controller brushes are equipped. withn t directlyacting clutch, which starts its assfciated brushes when the 'clutchmagnet is cm1-god and-stops them cates and the switch accomplishes itsel`ectrlcal cycle in one-half revolution, there rcsult from the fournotches but two stop positions, first with a brush upon the fortysixthsmall segmen'., 230,and second with the same brush .upon the ffteth orsmall assist in the identiiicalion and shown in Fig, 10.

f cally, preferably.

' is shown attache segment, 231, the companion brush in each instancebeing upon the long segment 232.

The switch of Fig.' 9 is the division starter und linesequencecontroller. 'lhe pilot clutch magnets of thel connective' divisions whennormal are charged only through `the starter. 'lhe clutch magnet of thefirst connective division is shown at 215 in Fig. 2, being connected towire 121, which is shown attached to cylinder point 3X6 in Fig. 9; thccorresi'iondingwire of a second division is shown attached to 'cylinderpoint 7X6 in Fig. The division of Fig. 2 is further associated with Fig.9 by the wire 128 shown attached to cylinder point 3X3 in F ig. 9; thecorrespondin wire of a second division to'cylinder point 7X3 in Fig. 9.These two wires upon cylinder points 7X6 and 7X3 in Fig. 9 nrcillustrative of a second complete division such as shown in Figs. 1, 2,4, 5, 6 and parte of Fig. 3. The starter is sole per group of divisions,(say six to twelve) and per associated group of lines (say one hundred).

' The esclusiva line telephone.

The automatic substation telephone com prises the usual items of atelephone set, and 1n addition an automat-ic call sender. The circuitsfor an exclusive-line telephone are Grounded brushes, 240, of which.four are shown, are adjustable by projecting buttons moved by thetelephone 4u'ser accordlng to indicators to place ground upon one pin ineachsegment (about a quadrant, as drawn) ofa circ'le of pins 241, whichcontains several ,such segments,.and upon which a. con# stes.-

'ihe devices of the central oice are ada-.pted'to' send. forty-twoimpulses for the control of the calLsender escapement, fortyonei fromthe signal controller and one from conjimuta or No. 8.

To set he signal transmitter to effect. connection th a desiredtelephone substation, @the indic `oir-*buttons are set tothe directorynumber f that substation by moving the buttons iride endently topositions in -Which they will in cate the desired directory num-.connective divisions, y the crank which winds Leemans ber. The wiresfrom the first two indicator points of each set to the contact pins inthe circle engaged by the erm 242 are shown in the diagram, Fig. 1 0.The remaining points are connected in corresponding manner, except thelast or tenth point, (directory numbcr 9 which is left unconnected.Contact nrm 242 normally engages the pointl 243 and thus normally holdsthe talkin bridge subject to contro by the hook switch 246. Connectionfrom the first conductor of the line 42,1, to the arm 242 ismovedforward mechanically one step by lthe operation of starting a call, itengages a contact pin 244 which is connected directly to earth orthrough a return wire to minus battery.

A switch, 247, composed of a pair of contact springs, is adapted .whenclosed, to complete the circuit for the stepping magnet `248 from thesecond conductor of the line 4,22, to earth. The springs of the switch24"( normally are disengaged from cach other but are forced intoengagement by means of a cam lever 249 moi-'ed by n. cam disk 239 curedto the shaft of the contact arm 242- A notch in the cam disk 239 permitsthe springs of the switch 249 and to disengage arm 242 stands in the inconnection with pin themselves when the normal. position, or 243. Whenthe zii-.11

.-242 is moved from its normalposition, bly;

the action of starting the call, the cam dis 239 operates the lever 249to close the switch 247, the disk 239 then. preserving the closedcondition of the switch 247 until the arm 242 completes its revolutionand resumes its engagement-with the pin 243. l

The lines entering a central office are divided into groupsof, say, onehundred lines per group, and the' automatic equipment of also, eachgroup of apparatusl serving a group of telephone lines; such a group ofapparatus is called simply a section. I

In each such section the switches for the most Vpart are each lgroup 'ordivision constituting a. connective unit analogous to a switchingAcordair e uiplnent i-n-"a manual telephone switc board. T he automaticswitches whichmake up .a connective unitor connective division in the247 to move the arm' a switchboard section, or

grouped into .groups called the central oiiice is for the most partdivided '105 figures ofthis application az-ei: primaryconnector orA-lineswitch', Fig; 15 pilot switch and thousands or ringing reglster,A Fig.2;

relays, ti'mer, lamps, condensers, resista-nces,

Fig. 3, signal controller, Fig. 44; interconneetor, Fig. 5; secondaryconnector or B-line switch, Fig. V6.

The automatic' switches of a section, common to all divisions, aredecimal register controller, Fig. 8; division starter. Fig. 9.

The total process of connecting two lines lib line'.

automatically in such an office comprises: (Il) A primary adjustment bywhich a connective division associated with a calling (2) Selectiveadjustments by which circuitrselecting switches are adjusted to selectSuch circuits as Will result ultimately7 in associating the. connectivedivision with the line desired by the calling line and indicated bythepreliminaryma'nual adjustment ol its `call sender. (3) Test andpreliminary ring `by which the line selected is rung upon 'if not foundengaged. (sl) Repeated ring until the call is answered.

(tl) Restoration automatically of all parte l of the connective divisionafter conversation and release. (7) rlln-ouglioutall of these loperations the coni'iective division superH i' circuits, or both.

the units set. The charging ol. a line r ing wires inl two se '40`electrical iiiotential upon -relay and the other paii vised. b v systemof lamp signals lwhich operate to announce normal action, and abnorl'nalaction, ifany. (S) The division is furtl'ier guardod i byautoi'natically `operative restoring or normaling circuits and deviceswhich act to restore it to normal condition for further service in eventof abnormal operation. (9) Specialservice requirements compel somecialis/.ation of apparatus or Early 'forms oli' decimal iniflicators,corrl str1 ed for one hundred lines', have comprised a.' rotating devicecapable of being stoliiped 1n one hundred dificrent positions,

. eacli position torresl'ionding4 to a line served by the device. Whenlthus stopped by a calling line, the decimal ind` fator identified thecalling line by placing an electrical po tential upon two identified.and line-identity?- i. l n Wires and one wlre being ltiltnitihcd in eachset. '.Ifhese sets were the decimal set and. tbe unit By the wireid'cm'tilied in the dect nia] set, the tens digit of the Iailing liuciti lied.

was made known, and by the wire ii ne callin the units son the unitedig-il'. of l ing linewas made linoivn. The biennal inthe tens setcorreapiindl .ing two 'coiuluctore which in turn identify the line, thesubsequent selection of the line being act n'lplished by a ctmmsetivodivisionupon fundanlel'ital principles lnnfetofore used 'Xssciiciated"with each line `l l y is a cut-oii` .elay l associated with cai. iunits 7wire is an add1tionalsignal relaya or Maintenance ot a,`condition tor conversation afl'ter the ring is answered and release `bysubscriber-s control.

each set comprising tpn quence relay, making .l bank of two hundred tenrelays in all required for a con'ipletely equipped decimal indicator forone hundred lines.

` (B) In the rotating decimal indicator the calling lines were serv idon either of the two principles of selectior. dependent upon thecircuits used. `The i 'st principle was `that the lines should be ser edin lrotation ast-hey might call, the search icing made in nulnericalorder and each call ng line being assigned to a connective divisionbefore the rotating decimal indicator prrceeded further in its search,the rotating,r evice being held mo tionless upon a callirg line so longras all. connective divisions w are engaged. The sec ond plan was thatlines should be served as in the first plan until all cornici-.tivedivisions became engaged, after which the rotating device would not stopupon any calling line until after a connective division had become idleand in cond tion to serve the line. The second plan therelore left l o amatter of chance the selection ol one calling line from several callinglines, when, all col'inective divisions having been bl sy, oneconnective diivision was released ald Inode available for serving one'of the sev ral calling lines. In my improved system, the lines arearranged in a series circuit in an order wl'uireby cer-- tain lines haveprecedence over all. others Aand are served in pretedencc when theconnective divisions are iusuliicient to serve all calling lines. Toguard against innnoderate use of the col'mectiie divisions by certailifavored lines'to the exclusion of lines less .favorably located upon theseries circuit, I provide a permutation de'vict` which from time to timechanges tl e order oi precedence of the lines and therebf distributesthe servs ice ot a group of conrective div .nous more uniformly amongthe lines served by that group.

(l) fl` accoi'nplish tl e peri'nuting require-` ments above recited b lutilizing the c vliitder switch ot the div sion starter. ln the drawingswhich accompany thi sperilration, I show the lowest six levels o'lE tbedivision starter cylinder tlius utilized.

(D) The full economy o't' a trunk circuit, having' a minimum nl mbcr ofconductors. :in an autolnatirl telephone exchange ran be realizedattiules only by usingsomo one conductor for more than one function inthe in'ogress Vo1 setting up, maintaining and disrluiling a" connectiei. l 'have met a reouirement oi this natu 'e by using the same conductorfor the operation of the clutch of a test switch and for a busy-testconductor o ,'ering a condition s litable for electrical `test todeteru'iine whetl er the distant switch is in normal position 1'otherwise. As the conductor thus used w ll vary its l'iotential fromtime to time as operating currents do found to test engaged. or free.

or do not pass over it to control the distant switch, 1t necessary forthe testmgVcircuit at any moment to show that the distant.

switch is engaged, regardless of the variations of potential upon ,theconductor serving the double purpose of switch control and lousy test. Ihave provided. three different potentials in the automatic centraloliice ofV which two may be applied to the conductor in question forsuch switch control, the third being applied for test purposes thetest-and control conductor being so associated with apparatus that itwill be entirely isolated only when the distant switch is idle, so thatno current will flowfrom the testing devicesy to the wire invquestionvif the switch be idle but tan'rent. will flow from the test devices toeither of the two operating potentials `if.

the switch be busy.A By the iow of current from the test device, it maybe known that the distant switch is busy and the test device may becontrolled in accordance therewith.

(F) In the automat-ic telephone4 system shown in the accompanyingdrawings it is necessary to adjust the selecting switches to variantpositions according as selected line If the tested line be found.engaged, the pilot switch is advanced-immediately after the test, but ifthe tested line be found free, the signal controileris advancedimmediately`- after the test and the pilot switch is advancedsubseiplently.

To provide ample timefor moving these switches to their position ofadjustment in accordance with the result of the test upon the selectedline` I provide a locking test relay which by lockingA w'ill record theresult of the ter'st indefinitely or for such a length of time as may berequired for the adjustment of the selective switches involved.

To insure the maintenance of the locking circuit for a sufiicient timeto mve`the pilot switch, I carry the llocking circuit throughA thepilotswitch.

(G) 1n my improved system of commutators for ringing in code manner uponparty `lines., I provide commutators each of which produces-a group ofimpulses arranged in a code manner,'and I cause these commutators torepeat each group of 'impulses as frequently as feasible. Inorderthat-the code ring upon a telephone line may be repeated lessfrequently, I provide an auxiliary comniutator. My auxiliary cominutatoris so designed and so connected inthe circuitsv of the ringingdevicesltli'at it p,ermits"the op! eration from timeto time of one groupof the code impulses, withholding theoperation of the interveningrepetitions of the group. I do this by connecting in series in a singlecircuita fast and a slow comn'ultator,x and so associating thecommutators that the vslow commutatof'will be closed `during onecvcle ofthefast commutator and `be open for ar predetermined number ofsucceeding cycles.

^ I provide also in the pilot switch tworinging positions. In the .tirstringing position, the fast commntators are effective to ring at alltimes; and I-provide means for permitv ting the pilot switch to remain'in this position during one and one only cycle of the fast commutators,thus attaining a single initial code ring, with. a minimum ,of delaybefore such initial ring. v

In my improved system of controli -ling circuits I provide four stop'positions for the pilot switch in which the further movement of thepilot switch, and therefore the entire command ofthe connection, isunder controlof either of thetwo connecte'd telephones.

next position, pilot vstop No.1() is,l held Inthe first position, pilot,.stop No. 9, the. lifting ofcithertelephone from the hook will advancethe piiot. Y The when the Adine telephone is of the hook and the B-linetelephone is on the hook. The third position, pilot stop No, 1'1 is held-when the vA-line telephone is on ythe hook Iand the B-linetelephone isolf `the hooi;v The fourth position, pilot stop No L? is held when bothtelephonesfare oli' the hook and the pilot switch is advanced by hang--ing up either telephone. Advantages are 'formed in the control of thevisual signals indicating the condition ofthve connection, andadvantages are foundin the complete system of control by'whichconnection atl all times is under complete controlA by either telephonewithout any operation other than the usual hook-switch operations commonin either automatic or manual telephone usage. (K) In association with aconnective di-- vision, I provide a` set of signal lamps and a system oflamp signals by which the condition of the connective division may beknown. These lamps -are mounted ,prominently upon the frames supportingthe switchesand in such manner `that an attendant seated in asupervising position may see from the one view point all the lamps of acentral ofiice or of his portion of a central office. In connection withthis plan, my system of lamp signals is such that the attendant bywatching the lamp signals may know to a very considerable degree theprogress made by any call which is received by the central officeapparatus. I provide three lamps and a normal call normally handled bythe central oiiice apparatus will produce illuminations of these lamps,or two of` them, in a predetermined order and of predetermined durationswhich may be recognized visually by'the attendant as indicating aconnective division and a telephone user`both acting in a normal manner.i

While a call terminating upon a line pre viously engaged (the calltherefore being defeated because of the guard or busy-test nais producedcondition upon the called line) may be corisidered in some ways as anormal call, I provide such details in iny system of4 lamp signals andcircuits thatthe sequence of sigwhen calling an engaged line isdifi'ei'ent'from the sequence of signals produced when calling an idleline. By this detail of improvement, an attendant Watch ing the lamps ofa distant olierating division, may know whether the call is terminatedupon an idle or a busy selected line..

I provide also a signal which is displayed when the subscriber upon theB-liue of the" connection lifts his receiver before the lifting of the.receiver' upon the A-line.. This is a condition having a peculiarinterest in an automatic exchange auf the charactei herein described. Myimproved signal for this condition also has a peculiar interest in thatfor the disjilay of this signal. I cause to glow simultaneously twolamps, neither of which indicates when glowing alone any part of thecondition ini'licatcd when both glow sinui'ltaneously.

Two lamps are provided to indicate normal operation of switches and a'third lamp is provided as an alarm lamp iiidicatiiner an abnormal'delay in the operation ofthe switches whether upon the part of centraloffice devices or npou't'ho users. f

(M) ,For Athe detection of automatic switches operating ab'nornnilly. lprovide. a timing device which is the equivalent of a slowly actingrrelay. the device beingrr so adjustedfthat itI will become operative assoon as an automatic switch becomes inoperative and that. itivillfbecome opera-tive."when the automatic switch reaches its normalgposition or any predetermined position. rl`.he relay contacts may beconnected in an alarm circuit or inV a circuit to restore the automatic.Switch to normal or both. 'l`heyspced oi operation o' the slow relay ortimiiii;Y device then may be adjusted to give the automatic switchsutlicient interval to operate in norlnal'm'ai'iner before the timingdevice closes its contact poi-nts. ily meansofsuch a device` anautomatic s wilch ma)v lue brought to the attention of au attluulautthro'i'igli the `alarm when the. switch is not inieriritingin normalniiannerfor at normal speed; or, on the. other hand. nuVautouiaticlswitch may be caused always to return 'to normal inreadiness For i'urt'heii service. in case it has not operated in Vnormalma'nuer and witliilra preiloteria-ined time limit.4

(N) l-eomhiie. in. .oney devi-cethe finir-.tions of an alarm timer an'dla.,i'eleastat'iliiei'.

I |-n-ovi'de.; in iiiy in-i'proved timer, two pairs of electricalcontact springs, and I provide a moving striker driven. 'stepby steptoward the springs. I so place the sl'iringswith reierence to VtheStriker that the striker en- .A gages end ol'oses the first pair of`springs part o'i telephone Vabnormal switches 4single bus wire. through`switch (Fig, l pr comprising four movable Contact poi-nts orupon apredeteri'uined step, and lso place the second pair ai' springs thatupon the next succeeding or some predetermined succeeding step, thestriker will engage and close the Asecoi'id iair of springs either directly or by movinplr the first pair of' springs or contact inen'ibursto engage the second pain* I thus cause mj' in'iproved timer -to closetwo circuits. each having a prialeterininet'l delay after the beg inningof operationof the timer, one circuit having a ,greater delay than theother it t esire-d. lt is obvious that both circuits may be closedsimultaneamsly if desired as an alternative method,.of'o'f eration.

lly means of the delay ot the second closingrr after the first7 I aluenabled so t0 c01inect my timer contict points, that an almorinalact-ion of indicated by an al: rm` and later is relieved automaticallyby re .-toration ol the switch. "r

may provide ai. automatic release and cause an alarm latei` i theautomatic release has not been el'ecti ce.

(P) When an au onnitic exchangev is fully Supervised, as in tile busyhours oi the day1 it may be desired -tliate\er v case of abnornialaction be studied by the attendant and that no automatic releasing bepermitted, a'll bei ng released and restoized manually by the attendant;in such :vease it is desirable Vthat the automat-ic release circuits otthe timers be disabled. )Viren the automati( exchange unattended asatnig'ht and on holidays, the alarm circuits associated witl'anto-matic. releasing de.- vices h'are no practical value andinay be.disabled, lea vingr the normalingroi` the automatic switches wlully tothe care ,of the timcr-controlled releasing1 circuits. 4It is obvious`limvei'er. tlt at the e.\'eliaii,fl'e should not be left at any timewithout eitheralarm or release circuits operative.

l provide in connection with my improved lamp-aiid-releasea switchhaving' two posi tions. in one position disabling the-'releasingcircuits of the entire Ve.\'c-liange` inV the other position disabling;rthe lamp-alarm circuits of the entire exchange. lI )rovide sul'icircuits for tli'e alarm that they may be cloni nected to a single. luiswi-i'e thronrh 'thenight switch. ,ln liliei main er I provide such acii'-, cuit for the release c rcuits of all the timer devices thattheynilvv be collected uporia the night switch.

' (Q) Tlpon the i1-ith level of thepilot )vide a. multiple brush brushfingers resting upon foiir of the fixed contact points of the level.These brushes in their progress cmnect together four points at alltimes, the. termined at any brushes'since all four rest an mtomatic.switch is first ou'r1 points bein detime by thegpi'isitionor lthe.

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